#define N_THR 4

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

/* From http://www.gnu.org/software/libc/manual/html_node/Hooks-for-Malloc.html */

/* Prototypes for __malloc_hook, __free_hook */
#include <malloc.h>

void* (*old_malloc_hook) (size_t, const void *);
 
/* Prototypes for our hooks.  */
static void my_init_hook (void);
static void *my_malloc_hook (size_t, const void *);
     
/* Override initializing hook from the C library. 
void (*__malloc_initialize_hook) (void) = my_init_hook; */
     
static void
my_init_hook (void)
{
  old_malloc_hook = __malloc_hook;
  __malloc_hook = my_malloc_hook;
}
     
static void *
my_malloc_hook (size_t size, const void *caller)
{
  void *result;
  /* Restore all old hooks */
  __malloc_hook = old_malloc_hook;
  /* Call recursively */
  result = malloc (size);
  /* Save underlying hooks */
  old_malloc_hook = __malloc_hook;
  /* printf might call malloc, so protect it too. */
  printf ("malloc (%u) returns %p\n", (unsigned int) size, result);
  sleep(1);
  /* Restore our own hooks */
  __malloc_hook = my_malloc_hook;
  return result;
}
     
/***************************/

/* Código de teste */

void* f_thread(void *v) {
  int thr_id = (int) v;
  int* s1;

  printf("Thread %d.\n", thr_id);  

  s1 = malloc(sizeof(int)* 100 * thr_id);
  return 0;

}

int main() {
  pthread_t thr[N_THR];
  int i;

  my_init_hook();
  
  for (i = 0; i < N_THR; i++) 
    pthread_create(&thr[i], NULL, f_thread, (void*) i+1);

  for (i = 0; i < N_THR; i++) 
    pthread_join(thr[i], NULL); 

  return 0;
}